Generally, a printer-slotter of this kind comprises various units which are separably connected according to the processing conditions. These units include a feeding unit having a kicker for kicking stacked sheets of corrugated paper successively from the lowermost sheet, a plurality of printing units for printing on the sheets sent from the feeding unit, a creaser-and-slotter unit for forming creasing lines or slots at desired locations on the sheets sent from the printing units, and a palletizer for gathering the processed sheets. When each unit is connected, adjacent units are successively coupled together with gears. Under this condition, the coupled units can be driven by a drive mechanism included in the feeding unit. The kicker of the feeding unit is reciprocated by the drive mechanism via a crank mechanism to kick the sheets of corrugated paper lying on a table. The printer-slotter takes the point at which the kicker of the feeding unit kicks as its home position. With respect to other units, an origin forming the reference of processing is set on rotating cylinders on which press plates or processing blades are installed. When the printer-slotter is operated, the various units are placed in phase so that they can process sheets at given positions.
When preparations for a work or an inspection is made, the units described above are disconnected from each other. Then, the rotating cylinders are separately rotated to make a setting. Therefore, if the various units are simply coupled together, the home positions of the units do not agree, i.e., they are out of phase and arranged randomly. Under this condition, the machine cannot be run. In the past, therefore, the kicker of the feeding unit is first placed in its home position in which the kicker normally kicks after the various units are coupled together. Then, differentials mounted in the units are separately driven by servomotors, as described in Japanese Patent Laid-Open No. 32664/1985 filed by the present applicant. The home positions of the rotating cylinders for their respective units are detected by sensors, and the units are returned to their home positions. After the units are placed in phase in this way, the machine is run ordinarily.
The above-described method of determining the positions at which paper is processed has the following disadvantages. After the feeding unit is returned to its home position, the rotating cylinders for the units are returned to their home positions. In this way, two stages of adjustment are necessitated. In addition, it is not easy to correctly return the kicker to its home position. In particular, various units such as printing units are successively connected to the feeding unit. In this state, the kicker is returned to its home position. Therefore, the moments of inertia of other units are added to the moment of inertia of the driving mechanism of the feeding unit. As a result, the moment of inertia of the whole system is quite large. If the home position sensor detects the home position of the kicker, and if the motor of the drive mechanism is stopped from operating, the drive mechanism keeps rotating because of its large moment of inertia. The kicker will come to a stop after passing beyond its home position. Hence, it is not easy to accurately place the kicker in position. Secondly, the motor incorporated in the drive mechanism of the feeding unit has a large capacity so that it can drive other units connected in tandem to the feeding unit. For this reason, the motor is unsuited for fine adjustment of position. This also makes it difficult to accurately return the kicker to its home position. When the kicker shifts out of its home position, the produced error appears as the error of the whole printer-slotter even if the rotating cylinders for the units other than the feeding unit which are next adjusting means are accurately placed in their home positions. The result is that an error arises in processing sheets of corrugated paper.